Is it possible to connect two PCs via USB C?

To connect one Type-C device (one PC) with another Type-C USB device (or another PC) and expect some connectivity, at least one of the "Type-C link partners" must support so-called DRD - Dual Role Device. The DRD port advertises its dual role by continuously switching its CC (communication channel) pins from 5.1k pull-down (signifying a USB device) to 56k-22k-10k pull-up (signifying USB host with different VBUS supply capability). It does this flip-flop several cycles per second.

However, to be a DRD Type-C device, it must have TWO USB controllers inside, one of xHCI (host controller interface), and another of "DCI" type - device controller interface. The IO of these two controllers must be multiplexed at the USB port pins. Currently only a few products (notably the Intel SoC aka "atom cheery trail" family, and other mobile-oriented chips found in mobile phones) have this capability. If a PC is made of desktop line of processors, no DRD is available yet.

If both PC are of the same kind, no connection (and no harm) will happen.

If one Type-C PC has DRD functionality, it will pick the phase of its "flip-flop advertising" with the role that is opposite to the connected single-role device. If the connecting device is host, the DRD device will lock as device, and vice-versa. If both devices are DRD, the roles will be selected at random, and later should be switchable in software.

Ale..chenski

Posted 2017-06-03T15:57:40.007

Reputation: 9 749

If any newer Intel chipsets support DRD/DRP, I will be glad to correct my answer... – Ale..chenski – 2017-06-04T01:19:12.880

Thanks for the detailed response. I figured it's just easier to go with a USB 3 transfer cable then since it's very rare to find PC motherboards with native ThunderBolt support unless it's with an addin card variety which wouldn't work for my setup. – Brian – 2017-06-05T00:48:26.107

I found a datasheet for intel 200 series chipsets (Z270 on my motherboard), that states: the USB Host Controller can now be paired with a standalone USB device to provide dual role functionality. The USB subsystem incorporates a USB 3.0 device controller. This controller is instantiated as a separate PCI function and shares USB 2.0 port 1 and USB 3.0 port 1.

and furrther:

Bus 0: Device 20: Function 1 USB Device Controller (OTG)

Whether there are drivers for this I don't know ... – Luciano – 2018-02-10T17:44:58.777

Actually, after messing around on my computer, I found that the abovementioned PCI device is missing (disabled). But it may exist on other, more expensive motherboards. This was on an intel skylake platform. – Luciano – 2018-02-10T18:03:50.373

What about Intel Kaby Lake chips, e.g. 8250? Do they support DRD?

– Suncatcher – 2020-02-04T10:06:06.000

@Suncatcher Not sure about 8250, but Z8xxx series of SoC (CherryTrail/CherryView ) were designed for ultra-light mobile devices. They used to have Dual-Data-Role (they have a USB Device Controller) and intended to operate over a single Type-C port in all modes. – Ale..chenski – 2020-02-05T02:22:34.787

Will try and report about the results – Suncatcher – 2020-02-05T07:25:26.060

Paging @AliChen. – Spiff – 2017-06-03T22:01:22.140

Beware that the mere presence of a USB Type-C connector doesn’t necessarily tell us much about what that port is really capable of. Do you have any indication whether or not they’re Thunderbolt 3 ports? – Spiff – 2017-06-03T22:04:54.773

Yea after some research I realized it's the TB circuitry that dictates who is client/server based on faux Ethernet IP addresses on the Thunderbolt adapter. – Brian – 2017-06-05T00:46:40.867

Is it possible to connect two PCs via USB C?

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